Apparatus, system, and method for aftertreatment control and diagnostics

ABSTRACT

A method includes providing an exhaust stream for an internal combustion engine, where the exhaust stream is fluidly coupled to an aftertreatment component. The method includes optically determining an amount of an exhaust gas constituent in the exhaust stream. The method further includes modifying a model stored on a computer readable medium in response to the amount of the exhaust gas constituent. The model is an engine NO x  generation model, a catalyst NO x  storage model, a catalyst NO x  conversion model, a catalyst NO to NO 2  conversion model, a catalyst conversion efficiency model, an engine soot generation model, and/or a urea hydrolysis model.

RELATED APPLICATION

This application is related to, and claims the benefit of, U.S.Provisional Patent Application No. 61/197,897 entitled “Apparatus,system, and method for detecting engine fluid constituents” and U.S.Provisional Patent Application No. 61/197,898 entitled “Optical sensingin an adverse environment,” both filed on Oct. 31, 2008 and bothincorporated herein by reference.

BACKGROUND

Reliably monitoring exhaust gas constituents related to aftertreatmentsystems for internal combustion engines presents several challenges.Frequently, exhaust environments operate at very high temperatures thatpreclude use of many standard sensor types. Further, engine combustionconstituents typically include soot and unburned hydrocarbons that canhamper operation of various sensing technologies. Present sensingtechnologies cannot detect various constituents of the exhaust gas andsurvive the exhaust environment. Various aftertreatment systems andtechnologies for internal combustion engines experience wear, failure,and operational variability that affect the final emissions of theengine-aftertreatment system. Presently available sensing technologieshave very limited feedback for aftertreatment systems, making controland diagnostics for aftertreatment systems difficult. Thus, there is anongoing demand for further contributions in this area.

SUMMARY

One embodiment is a unique method for determining an aftertreatmentcomponent performance in response to an optically determined exhaust gasconstituent amount, and modifying and engine operating parameter inresponse to the aftertreatment component performance. Furtherembodiments, forms, objects, features, advantages, aspects, and benefitsshall become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a system for detecting engine fluidconstituents.

FIG. 2 is a schematic illustration of an device for detecting enginefluid constituents.

FIG. 3 is a schematic diagram of a controller structured to determine aconcentration of a component of interest.

FIG. 4 is an illustration of a constituent wavelength response.

FIG. 5 is a schematic flow diagram of a procedure for determining aconcentration of a component of interest.

FIG. 6 is a schematic flow diagram of a procedure for designing anapparatus for determining a concentration of a component of interest.

FIG. 7 is a schematic flow diagram of a procedure for replacing anapparatus for determining a concentration of a component of interest.

FIG. 8 is a schematic flow diagram of a procedure for determining aplurality of fluid indices.

FIG. 9A is a schematic diagram of an apparatus for cleaning an opticalelement.

FIG. 9B is a schematic diagram of an apparatus for cleaning an opticalelement.

FIG. 9C is a schematic diagram of an apparatus for cleaning an opticalelement.

FIG. 10 is a schematic diagram of a system for determining a componentperformance and adjusting an engine operating parameter.

FIG. 11 is a schematic diagram of a component performance controller.

FIG. 12 is a schematic flow diagram of a technique for diagnosing acomponent.

FIG. 13 is a schematic diagram of an apparatus to determine an exhaustgas constituent at spatially divided portions of an exhaust stream.

FIG. 14 is a schematic diagram of another apparatus to determine anexhaust gas constituent at spatially divided portions of the exhauststream.

FIG. 15 is a schematic flow diagram of a technique for modifying a modelin response to an amount of an exhaust gas constituent.

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, any alterations and further modificationsin the illustrated embodiments, and any further applications of theprinciples of the invention as illustrated therein as would normallyoccur to one skilled in the art to which the invention relates arecontemplated and protected.

FIG. 10 is a schematic diagram of a system 1000 for determining acomponent performance and adjusting an engine operating parameter. Thesystem includes an internal combustion engine 1002 producing an exhauststream 1004 and having aftertreatment components 1006, 1008. Theexemplary system 1000 includes a turbocharger 1014 and an exhaust gasrecirculation (EGR) stream 1020 with an EGR valve 1022 that controls aflow rate of EGR. The system 1000 includes an intake stream 1018 for theinternal combustion engine 1002. The system includes an injector 1010that injects a reductant and/or reagent into the exhaust stream 1004,and a reductant (or reagent) storage vessel 1012. The storage vessel1012 may be a urea storage vessel, a fuel tank of a vehicle wherein theinternal combustion engine 1002 is installed, or any other vessel havinga reductant (or reagent) known in the art.

The system 1000 includes a component performance controller 1024 incommunication with one or more optical sensors 1016 to determine anamount of an exhaust gas constituent. Optical sensors 1016, as usedherein, indicate any sensor utilizing electromagnetic waves in theinfrared, visible, and ultraviolet frequency ranges of electromagneticradiation. The placement of optical sensors 1016 is exemplary, and anoptical sensor 1016 may be positioned anywhere within the system whereinan exhaust gas constituent determination is to be made. The amount ofthe exhaust gas constituent may be described as a fraction, percentage,concentration, or absolute mass of the constituent as understood in theart. The component performance controller 1024 may be in communicationwith any component of the system, and may further be an aftertreatmentcontroller and/or the engine controller. The component performancecontroller 1024 may be a single controller, a plurality of distributedcontrollers, and may have certain functionality implemented in hardware,software, or both.

FIG. 11 is a schematic diagram of an apparatus 1100 including acomponent performance controller 1024. The apparatus 1100 a performanceanalysis module 1102 that determines a component performance description1108 in response to an amount of the exhaust gas constituent 1106determined with an optical sensor 1016. The performance feedback module1104 provides an engine parameter adjustment 1110 in response to thecomponent performance description 1108. In certain embodiments, thecomponent performance description 1108 is a functional performancedescription of a physical component 1116. For example, the physicalcomponent may be a NO_(x) adsorption catalyst, a NO_(x) conversioncatalyst, an NO—NO₂ conversion catalyst, an oxidation catalyst, a sootfilter, and/or a reductant injector. Non-limiting examples of thefunctional performance description of the physical component 1116include a catalyst conversion efficiency value, a catalyst storagecapacity value, a filter integrity value, and/or an injection compliancevalue.

In certain embodiments, the component performance description 1108 is afunctional performance description of a model 1118, and the performancefeedback module 1104 adjusts an engine operating parameter by providinga model modification 1112. Non-limiting examples of a model include anengine-out soot model, an engine-out NO_(x) model, an engine-out NO_(x)composition model, a NO_(x) adsorption model, a NO_(x) release model, aNO_(x) conversion model, a hydrocarbon oxidation model, an ammonia slipmodel, an unburned hydrocarbon slip model, an ammonia:NO_(x) ratiomodel, and/or a urea hydrolysis model.

An exemplary embodiment includes the amount of the exhaust gasconstituent 1106 as an amount of ammonia and an amount of NO_(x), thecomponent performance description 1108 as an ammonia:NO_(x) ratio, andthe engine parameter adjustment 1110 as a urea injection rate.

Another exemplary embodiment includes the performance analysis module1102 determining the amount of the exhaust gas constituent 1106,determining the component performance description 1108 as afunctionality of an aftertreatment component in response to the amountof the exhaust gas constituent 1106, and the performance feedback module1104 providing a diagnostic output 1114 in response to the componentperformance description 1108. The diagnostic output 1114 can be anyvalue indicating the compliance or non-compliance of an aftertreatmentcomponent, and may be used by an engine controller to set a malfunctionindicator lamp (either ON or OFF), to set a maintenance lamp, to adjustengine controls, to store or clear a fault value, to increment ordecrement a fault counter, to trigger additional fault checking ortesting, and/or for any other purpose understood in the art.

FIG. 12 is a schematic flow diagram of a technique 1200 for diagnosing acomponent. The technique 1200 includes an operation 1202 to provide anexhaust stream for an internal combustion engine, the exhaust streamfluidly coupled to an aftertreatment component. The technique 1200further includes an operation 1204 to optically determine an amount ofan exhaust gas constituent in the exhaust stream, and an operation todiagnose an aftertreatment component in response to the amount of theexhaust gas constituent.

Various non-limiting examples of diagnosing an aftertreatment componentin response to the amount of the exhaust gas constituent are describedherein. One example is an operation 1206 to determine a catalysteffectiveness in response to the amount of the exhaust gas constituent.The catalyst effectiveness may be a catalyst adsorption effectiveness, acatalyst storage amount, and/or catalyst conversion effectiveness. Thecatalyst may be an oxidation catalyst, a NO_(x) adsorption catalyst, aNO_(x) conversion catalyst (e.g. lean NO_(x) or selective catalyticreduction), an NO—NO₂ conversion catalyst (a type of oxidationcatalyst), or a catalyzed soot filter.

Another example is an operation 1208 to determine whether a soot filterhas failed. In one example, the operation 1208 includes determining asoot amount and size downstream of a soot filter, and determining thesoot filter has failed if a soot amount or size exceeds a thresholdvalue. In certain embodiments, the operation 1208 includes determining asource of the soot in response to the size of the soot, for exampledetermining whether the soot is normal soot indicating a normalcombustion operation, or abnormally sized soot consistent with anexhaust gas recirculation failure, a combustion event failure, a fuelinjector failure, an injector 1010 failure where the injector placesunburned hydrocarbons in the exhaust stream 1004, and/or a failure of anoxidation catalyst 1006. One of skill in the art can simulate thefailures that are to be detected and determine the associated soot sizeprofile as a matter of straightforward data collection.

Another example is an operation 1210 to determine an injectorcompliance. The injector may inject a reductant or a reagent, and thetechnique 1200 includes the operation 1210 to determine whether theinjector is injecting the scheduled amount, is injecting with anappropriate response time, and/or is injecting with an appropriategeometric distribution in the exhaust stream. In a further embodiment,the technique 1200 includes determining whether the composition of theinjected material, e.g. urea, is compliant with expectations,regulations, and/or the system design. For example, the technique 1200can be utilized to determine whether a reductant vessel has been filledwith water rather than urea.

FIG. 15 is a schematic flow diagram of a technique 1500 for modifying amodel in response to an amount of an exhaust gas constituent. Thetechnique 1500 includes an operation 1502 to provide an exhaust streamfor an internal combustion engine, where the exhaust stream is fluidlycoupled to an aftertreatment component. The technique 1500 furtherincludes an operation 1504 to optically determine an amount of anexhaust gas constituent in the exhaust stream, and an operation tomodify a model stored on a computer readable medium in response to theamount of the exhaust gas constituent.

Various exemplary and non-limiting operations to modify a model inresponse to the amount of the exhaust gas constituent are describedherein. The modification to the model can include calibrating a modelingparameter, resetting a modeling parameter, and/or resetting anintegrator within the model. A modification operation includes theoperation 1504 determining an amount of soot and/or NO_(x) in theexhaust stream, and an operation 1506 to calibrate an engine sootgeneration and/or an engine NO_(x) generation model in response to thedetermined amount of soot and/or NO_(x). The operation 1504 to determinethe amount of NO_(x) may include determining an amount of NO_(x) and anamount of NO₂, where the engine NO_(x) generation model may includemodeling the amount of NO and the amount of NO₂ separately, and/ormodeling a bulk NO_(x) output of the engine. Various soot and NO_(x)estimators are known in the art that can benefit from real-timecalibration.

Another modification operation includes the operation 1504 determiningan amount of NO_(x), where the amount of NO_(x) is determined after aNO_(x)-affecting catalyst and potentially before the NO_(x)-affectingcatalyst. The modification operation includes an operation 1508 tomodifying a catalyst NO_(x) storage model, to modify a catalyst NO_(x)conversion model, and/or to modify a catalyst NO to NO₂ conversionmodel.

The operation 1508 to modify the catalyst NO_(x) storage model includesdetermining an actual storage rate based on the observed amounts ofNO_(x) versus the expected NO_(x), and can include operations such asdetermining a present storage rate, a total amount of NO_(x) stored, atotal amount of NO_(x) released, and/or a present release rate ofNO_(x). Models to estimate NO_(x) storage and release are known in theart and can be calibrated based upon NO_(x) determinations from aresponsive optical sensor that differentiates, for example, NO_(x) fromNH₃ (ammonia).

The operation 1508 to modify the catalyst NO_(x) conversion modelincludes determining an actual conversion rate based upon the observedamounts of NO_(x) versus the expected NO_(x), and potentially furtherbased upon an amount of NH₃ and/or an NH₃:NO_(x) ratio at a NO_(x)conversion catalyst. The operation 1508 to modify the catalyst NO to NO₂conversion model includes determining an actual conversion rate basedupon the observed amounts of NO and NO₂ versus the expected amounts ofNO and NO₂. The upstream amounts of NO and NO₂ may be measured orestimated (based upon the characteristics of the engine, for example)and the downstream amounts of NO and NO₂ are measured.

The technique 1500 includes an operation 1510 to determine the exhaustgas constituent at spatially divided portions of the exhaust stream.Referencing FIG. 13, a cross-section of an exhaust pipe 1302 having anexhaust stream 1004 is shown. A number of optical sensors 1016 a, 1016b, 1016 c determine an exhaust gas constituent at a number of spatiallydivided portions of the exhaust stream 1004. The optical sensors 1016 a,1016 b, 1016 c may be in any configuration to determine the exhaust gasconstituent at any position of interest in the exhaust stream 1004. Theuse of various optical sensors 1016 a, 1016 b, 1016 c distributedspatially around the exhaust stream 1004 allows determination ofphenomenon such as mal-distribution of a constituent (e.g. an injectedconstituent that does not distribute completely around the exhauststream 1004), puddling of a constituent, and/or accumulation of aconstituent.

Referencing FIG. 14, a number of optical sensors 1016 d, 1016 e, 1016 fdetermine an exhaust gas constituent at a number of spatially dividedportions of the exhaust stream 1004. The optical sensors 1016 d, 1016 e,1016 f may be in any configuration to determine the exhaust gasconstituent at any position of interest in the exhaust stream 1004. Theuse of various optical sensors 1016 d, 1016 e, 1016 f allowdeterminations of the constituent amount and/or concentration along theaxial trajectory of the exhaust stream 104, and allows determination ofphenomenon such as deposition or reaction of a constituent in anaftertreatment component, reaction of the constituent in the exhauststream 1004 (e.g. hydrolysis of urea from an injector 1010), and/orremoval of a constituent from the exhaust stream 1004 (e.g.un-evaporated droplets attaching to a sidewall of the exhaust stream1004 at a bend).

In a non-limiting example, urea is injected at the injector 1010 and theoptical sensors 1016 d, 1016 e, 1016 f determine whether the ureahydrolyzes in to ammonia. Where the urea remains along the exhauststream 1004, hydrolysis determined to be ineffective, where the urea isconverted along the exhaust stream 1004, the amount of urea drops andthe amount of ammonia increases and the hydrolysis is determined to beeffective. Where the urea disappears along the exhaust stream 1004 butammonia does not appear, it can be determined that the urea isaccumulating along the exhaust stream 1004, especially where otherinformation indicates that urea evaporation and hydrolysis may bemarginal (e.g. where the temperature of the exhaust stream 1004 is low).The amount of hydrolysis detected is utilized, in one embodiment, thetechnique 1500 includes an operation 1512 to modify a urea hydrolysismodel.

One of skill in the art will understand, based on the disclosuresherein, that a combination of radially distributed optical sensors 1016a, 1016 b, 1016 c and axially distributed optical sensors 1016 d, 1016e, 1016 f can be utilized to develop a three-dimensional picture ofexhaust gas constituent distribution in the exhaust stream 1004.

The detected exhaust gas constituent is urea, and the exhaust gasconstituent is detected at a plurality of spatially divided portions ofthe exhaust stream. The aftertreatment component diagnosis includesdiagnosing a urea accumulation condition, urea mal-distributioncondition, a urea injector failure condition, and/or a urea hydrolysisfailure condition. In certain embodiments, the technique 1500 includesan operation 1514 to diagnose a reductant injector in response to theamount of the exhaust gas constituent. In certain embodiments, theaftertreatment component diagnosis includes diagnosing a compositionsensor by determining an amount of the exhaust gas constituent measuredby the composition sensor and comparing the reading of the compositionsensor to the determined amount of the exhaust gas constituent. Forexample, the composition sensor can include an oxygen sensor and/or aNO_(x) sensor.

Any model calibration or modification operations known in the art arecontemplated herein including at least modifying a model parametervalue, selecting a model from a list of possible models, and/orresetting a model value such as an integrator. Tuning and modificationof models are useful provide better real-time performance of the modelsand related engine and aftertreatment operations, to determine when acomponent has degraded or failed, to enhance an On Board Diagnostic, toallow the engine or an aftertreatment component to operate in a moreefficient manner and/or to allow the engine or an aftertreatmentcomponent to compensate for an off-nominal operating condition.

The descriptions which follow, referencing FIGS. 1 through 9, includedescriptions of exemplary optical sensors capable of performing in aninternal combustion engine exhaust environment, including thetemperatures, soot, and other chemical constituents normally found in anengine exhaust environment.

FIG. 1 is a schematic diagram of a system 100 for optically determiningfluid constituents in challenging environments, including a fluidconduit receiving exhaust gas from an internal combustion engine. Incertain embodiments, the system 100 includes an engine 102 having asample channel (refer to FIG. 2) comprising a conduit 114 for an enginerelated fluid. The conduit 114 in the illustration of FIG. 1 is an EGRrecirculation path, and the engine fluid in the illustration of FIG. 1is recirculating exhaust gas flowing in the conduit 114. In certainembodiments, the conduit 114 may be any conduit having an engine relatedfluid therein, including, without limitation, an exhaust flow path 106,an engine intake path, a fuel line, a coolant line, a portion of anintake manifold, and an intake port for an individual cylinder of amulti-cylinder engine. In certain embodiments, the engine related fluidincludes engine exhaust gas, engine oil, engine coolant, recirculatingexhaust gas, fuel, engine intake gas, and/or engine intake gascorresponding to a single cylinder of a multi-cylinder engine. Incertain embodiments, the system further includes a device 112 fordetermining a concentration of a constituent of the engine fluid.Reference FIG. 2 for details of an exemplary embodiment of the device112.

In certain embodiments, the system 100 further includes a controller118. The controller 118 is structured to determine a concentration of acomponent of interest in the engine related fluid. The controller 118includes communications to sensors and actuators throughout the system100, and such communications may be through networks, datalinks,wireless communications, or other communication methods known in theart. The controller 118 may be a single device or distributed devices.In certain embodiments, the controller 118 includes a computer processorand computer readable memory of any known type. In certain embodiments,the controller 118 includes modules structured to functionally executeprocedures performed by the controller. The use of the term modulesemphasizes the implementation independence of the procedures. Modulesmay be elements of computer readable code, and may be grouped, divided,and/or distributed among various devices comprising the controller 118.Reference FIG. 3 for details of an exemplary embodiment of thecontroller 118.

In certain embodiments, the component of interest includes anitrogen-oxygen compound, a hydrocarbon, a sulfur containing compound,ammonia, a compound representative of a natural gas content, acarbon-oxygen compound, and/or an amount of particulates. For example,the compound of interest in certain embodiments includes methane andethane, and the controller 118 calculates a natural gas content inresponse to the amount of methane and ethane in the engine relatedfluid. In certain embodiments, the component of interest includesmethane, ethane, and/or propane. In certain embodiments, the componentincludes nitrogen oxide (N_(y)O_(x)), nitric oxide (NO), nitrogendioxide (NO₂), and/or nitrous oxide (N₂O). In certain embodiments, thecomponent of interest includes carbonyl sulfide (O═C═S), carbonmonoxide, and/or carbon dioxide.

In certain embodiments, the component of interest is componentindicative of engine wear, and the controller 118 is further structuredto determine an engine wear index in response to the concentration ofthe component of interest. For example, the compound of interest may bebrass (indicative of wear in certain bearings), iron (indicative of wearin certain engine blocks), a material known to be in the piston rings,and/or any other compound that indicates engine wear in a specificapplication.

In certain embodiments, the component of interest includes a componentindicative of fuel quality, and the controller 118 is further structuredto determine a fuel quality index in response to the concentration ofthe component of interest. For example, the compound of interest may benitrogen which in certain applications is indicative of a filler used innatural gas fuels. The concentration of nitrogen in the natural gas, incertain embodiments, can be indicative of the fuel quality. In anotherexample, the compound of interest may correspond to an additive, tracer,aromatic compound, or other compound in the fuel that in specificapplications may be indicative of a quality of the fuel.

In certain embodiments, the engine related fluid includes engine fuel orengine oil, and the component of interest includes sulfur or a sulfurcompound. In certain embodiments, the amount of sulfur allowed in theengine fuel and/or engine oil may be regulated, and the controller 118determines the concentration of sulfur in the fuel and/or oil to providethat information to an engine controller (not shown, but may be includedin the controller 118) for appropriate response.

In certain embodiments, the engine related fluid includes engine oil,and the component of interest comprises one of water and ethyleneglycol. In certain embodiments, the presence of coolant in engine oilmay be indicative of certain types of failure, and the controller 118determines the concentration of sulfur in the fuel and/or oil to providethat information to an engine controller (not shown, but may be includedin the controller 118) for appropriate response.

In certain embodiments, the engine related fluid includes enginecoolant, the component of interest includes a component indicative ofengine coolant quality, and the controller 118 is further structured todetermine an engine coolant quality index in response to theconcentration of the component of interest. The engine coolant quality,for example, may be a description of the water/ethylene glycol ratio,and may be utilized by the engine controller (not shown, but may beincluded in the controller 118), for example in a warranty assessmentafter an engine failure.

In certain embodiments, the engine related fluid includes engine oil,the component of interest includes a component indicative of engine oilquality, and the controller is further structured to determine an engineoil quality index in response to the concentration of the component ofinterest. For example, the component of interest may track the presentconcentration of an additive in the oil to determine when the oil shouldbe changed. In another example, the component of interest may include acompound or group of compounds from which an API number or othercharacteristic of the oil may be determined to evaluate the quality ofthe oil. In certain embodiments, the engine related fluid includes aengine oil, engine fuel, engine coolant, an exhaust gas fluid, arecirculating exhaust gas fluid, and/or an engine intake fluid.

FIG. 2 is a schematic illustration of a device 112 for detecting enginefluid constituents. The device 112 includes an electromagnetic (EM)source 214 structured to emit EM radiation through a first metal tube206. The EM radiation includes EM energy at a wavelength of interest. Incertain embodiments, the EM energy may be provided by a broad spectrumEM source (e.g. an incandescent source) and passed through aninterference filter 210 to remove frequencies outside the wavelength ofinterest. In certain embodiments, the interference filter 210 is abandpass filter removing frequencies outside a desired range offrequencies. In certain embodiments, the EM source 214 is a laser thatemits the EM radiation at a wavelength of interest and may not includean interference filter 210. In certain embodiments, the EM source 214 isa tunable laser that emits EM radiation at a number of frequencies ofinterest, for example to detect a number of components of interest. Incertain embodiments, the EM source 214 includes a plurality of sourcethat each emit a different wavelength, or the EM source 214 may be abroad spectrum emitter (e.g. the incandescent source), and a pluralityof interference filters 210 allow different wavelength ranges to thefirst metal tube 206 at different times to detect different componentsof interest.

In certain embodiments the EM source 214 includes at least one of alaser device, a light emitting diode, and a gallium arsenide lightemitting diode. In certain embodiments, the device 112 includes theinterference filter 210 disposed between the EM source 214 and thesample channel 114, with the interference filter 210 including a bandpass filter. In certain embodiments, the first metal tube 206 and thesecond metal tube 208 each comprise extruded aluminum, extrudedstainless steel, a polished metal, and/or a machined metal. The tubes206, 208 should have sufficient resistance to temperature and corrosionin the system 100, and have sufficient internal reflectivity to conveythe EM radiation to the sample channel 114 and back from the samplechannel 114.

In certain embodiments, the device 112 further includes an EM detector212 structured to receive a remainder radiation through a second metaltube 208, the remainder radiation including the remaining EM energy ofthe EM radiation after passing through the sample channel 114. Incertain embodiments, the second metal tube 208 may be the same physicaltube as the first metal tube 206, for example the EM radiation may passthrough the first metal tube 206, reflect off a mirror opposing theentrance of the first metal tube 206, and pass back into the first metaltube 206, which is then acting as the second metal tube 208, back to theEM detector 212. In certain embodiments, the EM detector 212 includes alead selenide detection device.

In certain embodiments, the device 112 includes a first window 202isolating the first metal tube 206 from the sample channel 114, and asecond window 204 isolating the second metal tube 208 from the samplechannel 114. The window material should be selected to allow sufficientEM energy through the window 202, 204 at the wavelength of interest thatthe EM detector 212 can distinguish the concentration of the componentof interest through the expected operational range for the component ofinterest, or the portion of the expected operational range that is ofinterest. For example, if the component of interest is oxygen in aninternal combustion engine application, the expected range may be zeroto twenty-one percent oxygen by mole, or a lower range if, for example,values above a certain percentage are not of interest in a particularapplication.

Factors that affect the final strength of the received EM radiationinclude the available power of the EM source 214, losses in theinterference filter 210, tubing 206, 208, the strength of the extinctionresponse of the component of interest at the selected wavelength, andthe optical path length across the sample channel 114. The material ofthe window 202, 204 should further be a material that withstands thethermal and chemical environment of the conduit 114, and further thatcan suitably conduct heat to allow a cleaning event (e.g. referenceFIGS. 3 and 9, and related descriptions) and withstand the cleaningtemperature of the cleaning event. The selection of a specific windowmaterial is dependent upon the application and is a mechanical step forone of skill in the art based upon the disclosures herein. In certainembodiments, the first window 202 and the second window 204 comprise amaterial selected from the group consisting of sapphire, glass, anddiamond. In one example, the component of interest is carbon dioxide,the engine related fluid includes combustion exhaust gases, thewavelength of interest is about 4.26 μ, the sample channel 114 has anoptical path length of about 35 mm, and the window 202, 204 material issapphire.

In certain embodiments, the first window 202 and the second window 204are the same physical window, for example where the first metal tube 206and the second metal tube 208 are the same physical tube. In certainembodiments, the device 112 includes a reflective device (e.g. a mirror,not shown) opposing the first window 202, for example where the firstmetal tube 206 and the second metal tube 208 are the same physical tube.

In certain embodiments, the system further includes a kit (e.g. as aportion of the device 112) having the first metal tube 206, the secondmetal tube 208, the first window 202, the second window 204, and atleast a portion of the sample channel 114. In certain embodiments, thekit further includes means for quick removal and replacement. Forexample, the kit may include wing nuts, levered clamps, seals, and/orother quick disconnect devices to allow ready removal of the kit andinstallation of a replacement kit. In certain embodiments, means forquick removal and replacement further includes positioning of the device112 within a system at a location where access is readily available—forexample positioning the device where the starter, turbocharger 110, fan,or other components in the application are not blocking access to thekit.

FIG. 3 is a schematic diagram of a controller 118 structured todetermine a concentration of a component of interest. In certainembodiments, the controller 118 is structured to determine a compositionindicator signal 310 in response to a strength of the remainderradiation and determine a concentration of a component of interest 346according to the composition indicator signal 310. For example, an EMdetector 212 receives the EM remainder radiation, the controller 118determines the composition indicator signal 310 based on the strength ofthe remainder radiation, and determines the concentration of a componentof interest 346 according to the composition indicator signal 310.

In certain embodiments, a controller 118 includes an electromagnetic(EM) source control module 302 structured to provide an EM pulse signal340. In certain embodiments, the EM source 214 emits EM radiationthrough the first metal tube 206 and the sample channel 114 in responseto the EM pulse signal 340. In certain embodiments, the EM detector 212receives the EM radiation from the sample channel 114 through a secondmetal tube 208, and provides a composition indicator signal 310 inresponse to a remaining radiation strength at the wavelength ofinterest. In certain embodiments, the controller 118 includes acomposition determination module 304 that determines a concentration ofa component of interest 346 according to the composition indicatorsignal 310. For example, in certain embodiments, the compositionindicator signal 310 may be an extinction value at the wavelength ofinterest, and the composition determination module 304 may utilize alookup table that determines the concentration of a component ofinterest 346 as a function of the extinction value. The lookup table iscalibrated according to the system 100 that the device 112 is installedin.

In certain embodiments, the EM source control module 302 provides an EMdiagnostic signal 342, and the EM source 214 emits an EM diagnosticradiation in response to the EM diagnostic signal. The EM diagnosticradiation includes energy at a diagnostic wavelength, and the EMdetector 212 provides a received diagnostic signal 312 in response to aremaining EM diagnostic radiation strength at the diagnostic wavelength.The diagnostic wavelength is a wavelength selected such that no expectedcomponents of the engine related fluid significantly absorb thediagnostic wavelength, except for “grey” or “black” components (e.g.components that absorb all wavelengths roughly equivalently). In manycircumstances, soot in the engine related fluid and debris deposited onthe windows 202, 204 can be treated as grey matter with sufficientaccuracy for many purposes.

In certain embodiments, the controller 118 further includes a diagnosticmodule 306 that determines an amount of soot 348 in response to thereceived diagnostic signal 312. In certain embodiments, the amount ofsoot 348 is determined by attributing an entire diagnostic signal 312strength loss, relative to a baseline diagnostic signal 312 strength, toabsorption by soot in the engine related fluid. In certain embodiments,the diagnostic module 306 determines an amount of debris 350 depositedon the windows (202, 204), determines a diagnostic signal 312 strengthloss attributable to the amount of debris 350, and determines aremainder of the diagnostic signal 312 strength loss as attributable tothe amount of soot 348.

In certain embodiments, the composition determination module 304determines the concentration of the component of interest 346 accordinga corrected composition indicator signal 316. In certain embodiments,the composition determination module 304 determines the correctedcomposition indicator signal 316 according to the equation:

$\begin{matrix}{{C\; C\; I\; S} = \frac{{Active} - {Dark}}{{Inactive} - {Dark}}} & \left( {{Equation}\mspace{14mu} 1} \right)\end{matrix}$

In the example Equation 1, CCIS is the corrected composition indicatorsignal 316, Active is the composition indicator signal 310, Inactive isthe received diagnostic signal 312, and Dark is a detected response at atime when the EM source 214 is not emitting EM radiation. For example,if the composition indicator signal 310 shows 70% (i.e. 30% absorptionof the wavelength of interest), the received diagnostic signal 312 shows90%, and the baseline response with the EM source 214 turned off is 2%,the composition indicator signal 310 is a value based on 70% while thecorrected composition indicator signal 316 is a value based on((70−2)/(90−2)) is 77%, or a little stronger than the directly indicatedcomposition indicator signal 310 due to suppression of the signal by anamount of soot 348 and/or an amount of debris 350.

In certain embodiments, the diagnostic module 306 determines the amountof soot 348 by filtering the received diagnostic signal 312 with a timeconstant less than 30 seconds to provide an Inactive fast responsesignal 318, filtering the received diagnostic signal 312 with a timeconstant greater than 30 seconds to provide an Inactive slow responsesignal 320, and determining the amount of soot 348 according to theInactive slow response signal 320 subtracted from the Inactive fastresponse signal 318. The 30-second value is exemplary only. The Inactivefast response signal 318 is an indicator of total grey matter in theconduit 114 (i.e. soot plus debris) and the inactive slow responsesignal 320 is an indicator of long term grey matter in the conduit 114(i.e. debris only). In certain embodiments, the inactive slow response320 utilizes a relatively slow rising time constant and a relativelyfast falling time constant, to bias the inactive slow response 320 to alower value in the observed range of inactive values (i.e. of receiveddiagnostic signal 312 values). In certain embodiments, diagnostic moduledetermines an amount of debris 350 accumulated on the window(s) 202, 204according to a lowest Inactive value 322 observed over time. Forexample, the diagnostic module 306 may track received diagnostic values312, and reset the inactive lowest value 322 to the lowest observedvalue over a recent period—for example a lowest value observed in thelast five minutes, or a lowest value observed during the most recentengine motoring event (i.e. when the engine was last not combusting anyfuel).

In certain embodiments, the controller 118 further includes a windowcleaning module 308 that provides a window cleaning index value 326 inresponse to the amount of debris 350 accumulated. In certainembodiments, the window cleaning module 308 is further structured toprovide a window cleaning request signal 344 in response to the windowcleaning index value 326 exceeding a cleaning threshold value 328. Incertain embodiments, the system 100 includes a window cleaning meansthat cleans the window(s) in response to the window cleaning requestsignal 344.

In certain embodiments, the diagnostic module 306 determines a faultvalue 330, an engine wear index 332, a fuel quality index 334, an enginecoolant quality index 336, and/or an engine oil quality index 338 inresponse to the concentration of the component of interest 346. Incertain embodiments, the fault value 330 is an indication whether anengine 102 parameter is out of tolerance according to theconcentration(s) of the component(s) of interest 346. In certainembodiments, the indices 332, 334, 336, 338 provide a value correlatedto the underlying engine parameter—i.e. engine wear, fuel quality,engine coolant quality, and/or engine oil quality—according to theconcentration(s) of the component(s) of interest 346.

FIG. 4 is an illustration 400 of a constituent wavelength response. Theillustration 400 includes a response value 412 versus a wavelength (orpossibly frequency) value 414 for a component of interest. Theconstituent wavelength response illustrated in FIG. 4 is consistent witha simplified illustration for carbon dioxide, showing a first responsivewavelength 408 and a second, stronger, responsive wavelength 410.Depending upon the parameters of the system 100 (refer to the sectionreferencing FIG. 2), a wavelength of interest for the EM radiation fromthe EM source 214 may be selected at either responsive wavelength 402,404. In certain embodiments, the sample channel 114 may be too long, orthe constituent concentrations expected may be too high, such thatinstead of using the stronger response wavelength 410, the weakerresponse wavelength 408 may be selected.

In certain embodiments, the wavelength of interest may be selected asone of the responsive wavelengths, for example selecting wavelength 402and/or 404. In certain embodiments, the wavelength of interest may beselected as a wavelength near one of the responsive wavelengths, forexample selecting wavelength 406. In certain embodiments, the wavelengthof interest such that an extinction of the wavelength of interest isabout 50% of an extinction of the responsive wavelength near thewavelength of interest (e.g. about what the wavelength of interest 406indicates in FIG. 4). The extinction of the responsive wavelength may bemeasured as a peak value (e.g. a discrete value right on the responsivewavelength 408), or as an area under (or above) a range of wavelengthvalues, such as a range of values allowed through the bandpass filter210.

The selection of an off-nominal wavelength such as the wavelength ofinterest 406 allows for longer sample channel 114 lengths, detection athigher constituent concentrations, and similar adjustments. Thewavelength of interest may be variable or multiple in certainembodiments, for example providing higher extinction rates at lowerconstituent concentrations and lower extinction rates at higherconstituent concentrations, or providing higher and lower extinctionrates at all times and utilizing both extinction rates in calculating acomposition indicator signal 310. In certain embodiments, the responsivewavelength includes a fundamental wavelength and/or a harmonicwavelength.

The schematic flow diagrams (FIGS. 5-9) and related descriptions whichfollow provide illustrative embodiments of operations related to thepresent application. Operations shown are understood to be illustrativeonly, and operations may be combined or divided, and added or removed,as well as re-ordered in whole or part, unless stated explicitly to thecontrary herein.

FIG. 5 is a schematic flow diagram of a procedure 500 for determining aconcentration of a component of interest. In certain embodiments, theprocedure 500 includes an operation 502 to isolate the first metal tubefrom the sample channel with a first window and isolating the secondmetal tube from the sample channel with a second window. In certainembodiments, the procedure 500 further includes an operation 504 toselect a wavelength of interest, and an operation 506 to select adiagnostic wavelength.

The procedure 500 includes an operation 508 to flow an engine relatedfluid through a sample channel, and an operation 510 to emit anelectromagnetic (EM) radiation comprising energy at a wavelength ofinterest through a first metal tube. The procedure 500 further includesan operation 512 to pass the EM radiation through a bandpass filter. Theprocedure 500 further includes an operation 514 to pass the EM radiationthrough the sample channel and an operation 516 to receive the radiationat an EM detector through a second metal tube. The procedure 500 furtherincludes an operation 518 to determine a composition indicator signal inresponse to a remaining radiation strength at the wavelength ofinterest.

In certain embodiments, the procedure 500 includes an operation 520 toemit an EM diagnostic radiation comprising energy at a diagnosticwavelength, and an operation 522 to receive the remaining diagnosticradiation strength at the diagnostic wavelength at an AM detector. Incertain embodiments, the procedure 500 further includes an operation 524to determine a diagnostic signal in response to the remaining diagnosticradiation strength at the diagnostic wavelength. In certain embodiments,the procedure 500 further includes an operation 526 to determine acorrected composition indicator signal. The procedure further includesan operation 528 to determine a concentration of a component of interestaccording to the composition indicator signal by utilizing the correctedcomposition indicator signal. In certain embodiments, the procedure 500further includes an operation 530 to check for whether concentrationsshould be determined for further components. In response to adetermination that concentrations should be determined for furthercomponents, the procedure 500 includes operations 510-528 to emit EMradiation at a second (or third, fourth . . . etc.) wavelength ofinterest, and to determine a concentration of a second component ofinterest in response to the EM radiation at the second wavelength ofinterest.

FIG. 6 is a schematic flow diagram of a procedure 600 for designing anapparatus for determining a concentration of a component of interest.The procedure 600 includes an operation 602 to determine a path lengthacross a sample channel, and an operation 604 to determine extinctionrates corresponding to responsive wavelengths for a component ofinterest at a design range of concentration. The procedure 600 furtherincludes an operation 606 to select a frequency of interest according tothe extinction rates corresponding to the responsive frequencies for thecomponent of interest at the design range of concentrations of thecomponent of interest. In certain embodiments, the procedure 600includes an operation 500 to determine a concentration of a component ofinterest, for example utilizing one or more operations from theprocedure 500.

FIG. 7 is a schematic flow diagram of a procedure 700 for replacing anapparatus for determining a concentration of a component of interest. Incertain embodiments, the procedure 700 includes an operation 702 toprovide a replacement kit comprising the first metal tube, the secondmetal tube, the first window, and the second window, and operations 704including removing a previously installed kit from an engine. Theprocedure 700 further includes an operation 706 to install thereplacement kit on the engine. In certain embodiments, the procedure 700includes an operation 500 to determine a concentration of a component ofinterest, for example utilizing one or more operations from theprocedure 500.

FIG. 8 is a schematic flow diagram of a procedure 800 for determining aplurality of fluid indices. In certain embodiments, the procedure 800includes an operation 500 to determine a concentration of a component ofinterest, for example utilizing one or more operations from theprocedure 500. In certain embodiments, the procedure 800 furtherincludes an operation 802 to determine whether a debris determinationmethod includes an inactive slow response or an inactive low amount. Inresponse to the procedure 800 including the inactive slow response, theprocedure 800 includes an operation 804 to determine an inactive slowresponse, and an operation 808 to determine a debris amount in responseto the inactive slow response. In response to the procedure 800including an inactive low amount, the procedure 800 includes anoperation 806 to determine an inactive low amount, and an operation 808to determine a debris amount in response to the inactive low amount.

In certain embodiments, the procedure 800 includes an operation 810 todetermine a window cleaning index value in response to the amount ofdebris accumulated. In certain embodiments, the procedure 800 furtherincludes an operation 812 to determine whether the window cleaning indexis greater than a cleaning threshold. In certain embodiments, theprocedure 800 includes an operation 814 to perform a window cleaningevent in response to determining the window cleaning index value exceedsa cleaning threshold value. In certain embodiments, the procedureincludes an operation 816 to determine a fault value in response to thereceived diagnostic signal. In certain embodiments, the procedure 800includes an operation 818 to determine an engine wear index 818, anoperation 820 to determine a fuel quality index, an operation 822 todetermine an engine coolant quality index, and/or an operation 824 todetermine an engine oil quality index in response to theconcentration(s) of the component(s) of interest.

FIG. 9A is a schematic diagram of an apparatus for cleaning an opticalelement. The apparatus 900 includes the optical element 202 and a meansfor cleaning the optical element. In certain embodiments, the apparatus900 includes a wire 902 with a high thermal expansion coefficient, andthe wire is positioned to sweep the optical element 202 upon atemperature increase event. In certain embodiments, the wire 902 may bea resistive wire that heats when a supply voltage 904 is applied,sweeping the wire 902 across the optical element 202.

FIG. 9B is a schematic diagram of an apparatus for cleaning on opticalelement. The apparatus 901 includes the optical element 202, which maybe a sapphire cylinder. In certain embodiments, and a tube 206. Incertain embodiments, a ceramic filler 908 or other heat resistantmaterial provides a seal between the optical element 202 and the conduit114. The apparatus 901 includes a means for cleaning the optical element202 including a resistive wire 905 wrapped around a portion of theoptical element 202, such that when the resistive wire 905 is heated theface of the optical element 202 exposed to the conduit 114 (i.e. the“window”) is heated sufficiently to drive debris (through oxidation,evaporation, or other means) from the face of the optical element 202. Asupply voltage 904 may be applied to the resistive wire 905 at timeswhere a cleaning event is performed.

FIG. 9C is a schematic diagram of an apparatus 903 for cleaning anoptical element. The apparatus 903 includes a resistive wire 910 inthermal contact with a mirror 912 positioned opposite an optical element202. The resistive wire 910 heats the mirror 912 sufficiently to drivedebris (through oxidation, evaporation, or other means) from the face ofthe mirror 912. A supply voltage 904 may be applied to the resistivewire 910 at times where a cleaning event is performed.

As is evident from the Figures and text presented above, a variety ofembodiments according to the present invention are contemplated. Certainexemplary embodiments of methods and apparatus for diagnosing anaftertreatment component, for adjusting an engine operating parameter inresponse to a component performance description of an aftertreatmentcomponent, and for modifying a model stored on a computer readablemedium are described. All embodiments are exemplary and non-limiting.

An exemplary method includes providing an exhaust stream for an internalcombustion engine, the exhaust stream fluidly coupled to anaftertreatment component, optically determining an amount of an exhaustgas constituent in the exhaust stream, and diagnosing an aftertreatmentcomponent in response to the amount of the exhaust gas constituent. Inone embodiment, the exhaust gas constituent includes NO_(x), anddiagnosing the aftertreatment component includes determining a catalysteffectiveness. The catalyst effectiveness may be a catalyst adsorptioneffectiveness and/or a catalyst conversion effectiveness.

In certain embodiments, the exhaust gas constituent is soot. Theexemplary method further includes diagnosing the aftertreatmentcomponent by determining that a soot filter has failed, and/or bydetermining a size of the soot. The method further includes determininga source of the soot in response to the size of the soot.

In an exemplary embodiment, the exhaust gas constituent includes NO(nitrogen-oxide), the method includes determining an amount of NO₂, anddiagnosing the aftertreatment component includes determining a catalystNO to NO₂ conversion effectiveness. In another exemplary embodiment, theexhaust gas constituent includes urea, and diagnosing the aftertreatmentcomponent includes determining a urea injector compliance and/ordiagnosing an injected urea composition.

In certain embodiments, the exhaust gas constituent is urea, and themethod further includes determining the exhaust gas constituent at aplurality of spatially divided portions of the exhaust stream.Diagnosing the aftertreatment component further includes diagnosing aurea accumulation condition, urea mal-distribution condition, a ureainjector failure condition, and/or a urea hydrolysis failure condition.In certain embodiments, the method includes diagnosing theaftertreatment component by diagnosing a composition sensor.

Another exemplary embodiment is an apparatus including an optical sensorstructured to determine an amount of an exhaust gas constituent in anexhaust stream of an internal combustion engine, a performance analysismodule that determines a component performance description in responseto the amount of the exhaust gas constituent, and a performance feedbackmodule that adjusts an engine operating parameter in response to thecomponent performance description. The apparatus includes the componentperformance description as a functional performance description of aphysical component. The physical component includes a NO_(x) adsorptioncatalyst, a NO_(x) conversion catalyst, an NO—NO₂ conversion catalyst,an oxidation catalyst, a soot filter, and/or a reductant injector. Incertain embodiments, the functional performance description includes acatalyst conversion efficiency value, a catalyst storage capacity value,a filter integrity value, and/or an injection compliance value.

In certain embodiments, the component performance description includes afunctional performance description of a model, and the performancefeedback module further adjusts an engine operating parameter bymodifying the model. The model includes an engine-out soot model, anengine-out NOx model, an engine-out NOx composition model, a NOxadsorption model, a NOx release model, a NOx conversion model, ahydrocarbon oxidation model, an ammonia slip model, an unburnedhydrocarbon slip model, and/or a urea hydrolysis model. The exhaust gasconstituent includes an amount of ammonia and an amount of NO_(x), wherethe component performance description includes an ammonia:NOx ratio, andthe engine operating parameter includes a urea injection rate.

Another exemplary embodiment is a method including providing an exhauststream for an internal combustion engine, the exhaust stream fluidlycoupled to an aftertreatment component, optically determining an amountof an exhaust gas constituent in the exhaust stream, and modifying amodel stored on a computer readable medium in response to the amount ofthe exhaust gas constituent. The modifying the model includescalibrating a modeling parameter, resetting a modeling parameter, and/orresetting an integrator. In an exemplary embodiment, the exhaust gasconstituent includes soot, and modifying the model includes calibratingan engine soot generation model.

In certain embodiments, the exhaust gas constituent includes NO_(x), andmodifying the model includes calibrating an engine NO_(x) generationmodel, modifying a catalyst NO_(x) storage model, modifying a catalystNO_(x) conversion model, and modifying a catalyst NO to NO₂ conversionmodel. In certain embodiments, the exhaust gas constituent includesurea, and the method further includes determining the exhaust gasconstituent at a number of spatially divided portions of the exhauststream. Modifying the model further includes modifying a urea hydrolysismodel.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly certain illustrative embodiments have been shown and described andthat all changes and modifications that come within the spirit of theinventions are desired to be protected. It should be understood that anyrelative characterization of embodiments such as but not limited topreferable, preferably, preferred, more preferred, advantageous, orexemplary utilized in the description above indicate that theembodiments or features thereof so described may be more desirable orcharacteristic, nonetheless the embodiments or features thereof may notbe necessary and embodiments lacking the same may be contemplated aswithin the scope of the invention, the scope being defined by the claimsthat follow. In reading the claims, it is intended that when words suchas “a,” “an,” “at least one,” or “at least one portion” are used thereis no intention to limit the claim to only one item unless specificallystated to the contrary in the claim. When the language “at least aportion” and/or “a portion” is used the item can include a portionand/or the entire item unless specifically stated to the contrary.

1. A method comprising: providing an exhaust stream for an internalcombustion engine, the exhaust stream fluidly coupled to anaftertreatment component; optically determining an amount of an exhaustgas constituent in the exhaust stream during the operation of theinternal combustion engine, the exhaust gas constituent comprising urea;and diagnosing the aftertreatment component in response to the amount ofthe exhaust gas constituent.
 2. The method of claim 1, wherein theexhaust gas constituent further comprises NO_(x), and wherein diagnosingthe aftertreatment component comprises determining a catalysteffectiveness.
 3. The method of claim 2, wherein determining thecatalyst effectiveness comprises one of determining a catalystadsorption effectiveness and a catalyst conversion effectiveness.
 4. Themethod of claim 1, wherein the exhaust gas constituent further comprisessoot.
 5. The method of claim 4, wherein diagnosing the aftertreatmentcomponent comprises determining that a soot filter has failed.
 6. Themethod of claim 4, further comprising determining a size of the soot. 7.The method of claim 1, wherein the exhaust gas constituent furthercomprises NO, the method further comprising determining an amount ofNO₂, and wherein diagnosing the aftertreatment component comprisesdetermining a catalyst NO to NO₂ conversion effectiveness.
 8. The methodof claim 1, wherein diagnosing the aftertreatment component comprisesdetermining a urea injector compliance.
 9. The method of claim 1,wherein diagnosing the aftertreatment component comprises diagnosing aninjected urea composition.
 10. The method of claim 1, further comprisingdetermining the exhaust gas constituent at a plurality of spatiallydivided portions of the exhaust stream.
 11. The method of claim 10,wherein diagnosing the aftertreatment component comprises diagnosing atleast one condition selected from the conditions consisting of: ureaaccumulation, urea mal-distribution, a urea injector failure, and a ureahydrolysis failure.
 12. The method of claim 1, wherein the diagnosingthe aftertreatment component comprises diagnosing a composition sensor.13. An apparatus, comprising: an optical sensor structured to determinean amount of an exhaust gas constituent in an exhaust stream of aninternal combustion engine during the operation of the internalcombustion engine, the exhaust gas constituent comprising urea; aperformance analysis module structured to determine a componentperformance description in response to the amount of the exhaust gasconstituent; and a performance feedback module structured to adjust anengine operating parameter in response to the component performancedescription.
 14. The apparatus of claim 13, wherein the componentperformance description comprises a functional performance descriptionof a physical component comprising a component selected from thecomponents consisting of: a NO_(x) adsorption catalyst, a NO_(x)conversion catalyst, an NO—NO₂ conversion catalyst, an oxidationcatalyst, and a reductant injector.
 15. The apparatus of claim 13,wherein the component performance description comprises a functionalperformance description of a physical component and wherein thefunctional performance description comprises a description selected fromthe descriptions consisting of: a catalyst conversion efficiency value,a catalyst storage capacity value, and an injection compliance value.16. The apparatus of claim 13, wherein the component performancedescription comprises a functional performance description of a model,and wherein the performance feedback module is further structured toadjust an engine operating parameter by modifying the model.
 17. Theapparatus of claim 16, wherein the model comprises a model selected fromthe models consisting of: an engine-out soot model, an engine-out NO_(x)model, an engine-out NO_(x) composition model, a NO_(x) adsorptionmodel, a NO_(x) release model, a NO_(x) conversion model, a hydrocarbonoxidation model, an ammonia slip model, an unburned hydrocarbon slipmodel, and a urea hydrolysis model.
 18. The apparatus of claim 13,wherein the exhaust gas constituent comprises an amount of ammonia andan amount of NO_(x), wherein the component performance descriptioncomprises an ammonia:NO_(x) ratio, and wherein the engine operatingparameter comprises a urea injection rate. 19.-23. (canceled)
 24. Theapparatus of claim 13, wherein the component performance descriptioncomprises an injection compliance value.
 25. The apparatus of claim 13,wherein the controller is further structured to diagnose an injectedurea composition in response to the exhaust gas constituent.
 26. Theapparatus of claim 13, wherein the optical sensor is further structuredto determine the exhaust gas constituent at a plurality of spatiallydivided portions of the exhaust stream.
 27. The apparatus of claim 26,wherein the controller is further structured to, in response to theexhaust gas constituent, diagnose at least one condition selected fromthe conditions consisting of: urea accumulation, urea mal-distribution,a urea injector failure, and a urea hydrolysis failure.